Method and apparatus for purifying paper pulp



y 4 'A. BEsEs 1 2,319,411

METHOD AND APPARATUS FOR PURIFYING PAPER PULP Filed July'5, 1938 Andre Be/ ge'a PatentedJulyS, 1945 METHOD AN!) APPARATUS FOR PURIFYING PAPER PULP Andre Borges, Lorp par St. Lizier, Arrlege, France; vested in the Alien Property Custodian Application July 5, 1938, Serial No. 217,628

11 Claims.

The invention relates to a method and an apparatus, for the uninterrupted cleaning and sitting in particular of paper-making pulp, and which is preferably inserted etween the vats and the point of entryof the ma rial into a paper making machine. Devices are "known in which the material or pulp to be treated, after introduction tangentially into a container, is set in rotation at a high speed and is carried first downward and then upward, the cleaned material being carried concentrically upward, the lighter impurities also upward and the heavier impurities being carried away downward.

The invention relates to a particularly advantageous embodiment of such a device, in which by a suitable construction of the feed of the ma-. terial or pulp and of the parts of the container,

. there takes placean effective and uninterrupted separation of the undesired matter contained in the material.

According to the invention, the inlet part which in cross-section has the form of a rectangle and the longer side of which is parallel to the axis of the container, is so fitted spirally on to the container that it is open towards the interior thereof and its outer wall merges, after approximately 360, into the container wall, there being furthermore provided two container parts, both widening out at first in conical form and being then made cylindrical, from the point where the material enters, one in the downward direction, and the other in the upward direction.

The part of the container widening out from below upwards is arranged concentrically in the conical part of the container part widening out from the top downwards, and on to the cylindrical part of the outer part of the container there is connected at the bottom a further part becoming smaller conically downward. At the level of the transition of the upper conical part into the cylindrical part of the outer part of the container, there is concentrically arranged in this a, hood Germany July 10, 1937 open towards the bottom and leaving free a comparatively narrow but high annular gap, the centre of which hoodmerges into a centrally arranged pipe of comparatively small diameter carried upwardly out of the container. The opening of the hood is screened from below by a plate. Above the inlet there is provided an annular space having an exhaust or outlet. At the lower conical part of the outer container there is connected at sluice valve which consists of a separate container communicating at the top by a slide or the like with the lower part of the main container and which is closed at the lower part by a further slide or the like. There opens into the lower part of the sluice valve container a water supply pipe adapted to be closed and in its uppermost part an air pipe also adapted to be closed. There furthermore opens into the lower part of the main container a supply pipe, adapted to be closed, for dilution water.

If the separation both of the lighter, as also of the heavier, constituents is to take place in the apparatus, there is provided concentrically within the cylindrical part provided at the top with an outlet, of the inner part of the container, and below the said outlet, a pipe merging at the bottom into a hood and carried at the top out of this part of the container.

If the apparatus is subdivided in such manner that on the one hand essentially the separation of the heavier constituents and on the other hand essentially the separation of the lighter constituents take place, then the two parts of the container are made as two separate containers only connected by a pipe if necessary provided with a pump. That one of these which essentially serves for the separation of the heavier constituents of the material is made according to the previous description but does not have the above mentioned pipe arranged within the inner part of the container. The other is provided at the bottom with a spirally shaped inlet for the material freed from the heavy constituents. It broadens out at first in conical form from below upward, then runs cylindrically and is provided at the top with an outlet which is arranged concentrically to a central pipe which runs within the cylindrical part downward in screen form and is carried out of the container at the top. Furthermore, the container is provided with a cone coming in from below, arranged concentrically and extending to the level of the screen, which is open to the outside and thus forms together with the outer container wall an annular space of cross-section increasing towards the top, the cone having at the bottom a cylindrical addition.

The invention is illustrated by way of example in the accompanying drawing in which,

Figure 1 is a vertical section through the apparatus,

Figure 2 is a horizontal section on the line 2-2 I of Figure 1,

Figure 3 is ,a-plan, and

Figures 4 and 5 are vertical sections through a modified subdivided apparatus, in which Figure 4 is a section through the apparatus which essentially serves for the separation of the heavier constituents, and

Figure '5 is a section through the apparatus which essentially serves for the separation of the lighter constituents.

In height the outer container I is subdivided into two zones A and B of which the zone A is formed by the part opening out conically downwards, and the zone B by the cylindrical part and the part connecting on downward and becoming smaller conically downward. The separation of the heavy constituents takes place in the part A and the separation of the lighter constituents in the part B: The supply of material or pulp takes place through the inlet 2 which, in order to attain as high a velocity of the material as possible is made in nozzle form and has the cross-section of a rectangle, the long side of which is parallel to the axis of the container,

and the shorter side of which is as short as possible i. e., in this case just so that the impurities, such as sand, metal particles, etc., pass through. In practice the dimension of the nozzle may be about mm in length. In order to obviate turbulence in the column of material rotating in the container, the inlet is so made that the inflowing material rests on the outside of the rotating column of material and only in the course of a revolution of about 360 gradually merges completely into the rotating column of material. Inside the container I is concentrically arranged the container or baiiie 3 first opening out from below upwards in conical form and then running cylindrically.

The heavy constituents: of the column of ma* terial are, in consequence of centrifugal action, thrown on to the wall of the container I and sink corresponding to the direction of flow, the conical shape of the part A and gravity to below the opening of the part or baiiie 3, i. e., to below the zone C-C, while the material freed from these constituents rises into the container part 3. The greater the centrifugal force, the more parts are separated. In consequence of the conical shape of the container zone A, an increasing centrifugal force can develop from the cross-section 2-2 to the zone (2-0. The material and water in the zone A thus represents a column which rotates in all parts with like angular velocity and the circumferential speed of which is consequently greater in the zone C-C than in section 2-2.

The parts A and B of the container I are separated by the baiile 4 which leaves free an annular gap 5. The annular gap 5 must be as narrow as possible, in order to create the possibility that the liquid in the zone B of the container I shall be carried away to the smallest possible extent by the rotating liquid in the part A. The lower limit of its width is, however, fixed by the nature of the heavy constituents which have to pass through. Consequently, the baflie wall forming one side of the gap is kept as high as possible. The baille 4 is supported by a centrally arranged tube 6 which is carried upwardly out of the container and is continued in a. pipe I. The heavy constituents pass through the annular gap 5 into the zone B of the container I, where only a slow rotation of the column of material takes place and the centrifugal force is practically equal to zero and where these constituents if they are capable of suspension are drawn into the pipe 6 and are carried away through the pipe I which has a valve or the like for regulating the suction efiect.

The escape of material through the tube 6 and pipe 1 produces in the annular space 5, a feeble current which is suflicient to draw into the zone B the heavier parts held by the centrifugal force below the zone C-C on the container wall and there slowly sinks due to gravity, so that they do not collect in the zone CC and do not pass into the baifie 3. The opening of the pipe 6 in the bailie 4 is baflled at the bottom by a baffle plate 8 and, furthermore, the pipes 6 and I are here of comparatively small cross-section, so that the suction efiect of the pipe I only extends to the circumference of the baflle 4 and no eddies are produced in the part B of the container in which the portions which are not capable of floating, sink down. The heavy constituents, such as sand, metal particles, etc., can be removed through a sluice valve, which consists of a container 5 which is attached to the part B of the container I by means of a slide valve III and which is closed at the bottom by a further slide valve II. In the lower part of the sluice valve there opens a water supply pipe I3 adapted to be closed by a valve I2, and in the upper part an air pipe I5 adapted to be shut oil by means of a valve I4. These two pipes have for their object to permit the sluice valve to be always completely filled with water before the opening of the slide I0, so that no injurious air enters on the opening of the sluice valve, into the container I. There furthermore opens into the container I a delivery pipe I! for dilution water, this pipe being closed by a valve iii.

The separation of the material from the lighter constituents, such as rubber, cork and other impurities, takes place in the container part 3, these collecting around the pipe 6 while the material collects more towards the wall of the container part 3 in which it rises following the flow. The lighter constituents pass into a pipe I8 broadening out at the bottom into a small baffie or flared end I9 arranged in the upper part of the container 3, and which is arranged concentrically relative to the tube 6, and are exhausted through the pipe 20 which-is provided with a regulating valve, not shown, by which they are carried to a supplementary cleaner or pulp salvaging device. The cleaned material passes, carried outwardly by centrifugal force, around the bafile I9 out through the annular space 2| and is exhausted through the pipe 22 to the paper making machine. A valve or slide, not shown, is provided in the pipe 22 for regulating the discharge.

Directly above the inlet 2 there is provided an annular space 23 which communicates through an outlet 24 with a discharge pipe, not shown, having for its object to remove any air which may enter the apparatus. Material leaving through the outlet 24 is again returned to circulation in the apparatus.

The operation of the device is all the more favourable the smaller the diameter of the annular space 2I as compared with the diameter of the container I directly below the inlet. These two diameters determine the velocity and thus also the inherent energy in the liquid in the inlet zone or respectively in the outlet zone. Consequently, the force at disposal in the container is dependent upon the difference of these two diameters. If the force is greater than the frictional resistances, the excess of the liquid rotating in the container zone A imparts an angular velocity which is the same in the zone C-C as in the vicinity of the inflow, but a circumferential velocity which is greater in the zone 0-0, The centrifugal force is most effective in the zone 0-0. The cross-section of the annular space 2| is thus kept as small as the construction and output of the apparatus permit. On the other hand, the diameter of the container below the inflow cannot be kept very large for the purpose of increasing the differences in diameters, since the size or amount of the centrifugal force is inversely proportional to the radius.

The apparatus thus operates under the following conditions:

In the zone A, where the centrifugal force is at a maximum, the separation of the heaviest parts is at its bes In the zone B, where .a circular movement takes place which corresponds to a centrifugal force of practically zero, and which is favourable for the separation based on gravity, there is a certain proportion of impurities which have been thrown out by a centrifugal force and drawn into the zone B and which have no suificient density to effect their precipitation. These impurities are carried away through the pipes 6, 1 and finally pass'on to the paper making machine, or the outflow from the pipes 6 and I may be delivered in a diluted condition by material return water in one or more similar machines. These auxiliary purifiers or machines work with very great dilution; consequently the separationof the heavy constituents in the zone B is better therein and the exhaust flow from the pipe I of such an auxiliary purifier, which is carried into the material circulation and 'flnally reaches the paper machine, not shown, contains considerably fewer constituents which cannot be precipitated. The light constituents drawn away through the pipe 20 are diluted with material return water, and then pass through one or more supplementary cleaners where the light constituents are separated before the pulp passes to the save-all.

As in the case of the apparatus described, the separation of the lighter constituents taking place in the since the centrifugal force is less in the container part 3 than in the zone'A of the container part I, if an effective separation of the lighter constituents is desired, the apparatus can be subdivided. The subdivision takes place preferably by the provision for the separation of the heavier constituents of a device which only differs from the one hitherto described by omitting the centrally arranged pipe l8 with the baille l9 and the exhaust pipe 20 for the lighter constituents. The outlet'22 of this apparatus communicates with the inlet 25 of a second apparatus, this if necessary with the interposition of a pump, not shown. This second apparatus which is intended for the separation of the lighter constituents consists of a container 26 the shape of which corresponds to the container part 3. The inlet 25 is arranged at the bottom but otherwise in the same way as with the container I.

side, and which from the bottom upward is firstmade cylindrical and then conical and extends by its tip up to the level of the bafile or hood 21 and thus forms with the outer container wall,

an annular space.

I claim: 1. Apparatus for continuous purification particularly of paper pulp comprising a'principal vessel of circular cross-section, a top member having an inlet of spiral form arranged circumferentially on said vessel adapted to introduce the paper pulp to be treated tangentially at high speed, said top member having an outlet for the' purified pulp centrally of said inlet, a circular container part 3 is less effective In the cylindrical portion of the container 26, there is a baflle 2'I corre- The outlet of the cleaned stufi bailie located concentrically within said vessel and below said outlet adapted to form therewith a comparatively narrow and deep annular gap and substantially dividing the vessel into two parts, said baflle having a central opening, and a central open-ended pipe of comparatively small diameter fitted in said opening and extending upwards through the top of the vessel.

2. Apparatus for purifying paper pulp comprising a vessel of circular cross-section,a top member having a spiral inlet on the periphery of said vessel, an annular wall depending from the top member, said top member having an outlet from said vessel from the space within said annular wall and arranged centrally relative to the inlet a baflle substantially dividing the lower part or said vessel beneath said annular wall from the upper part containing said annular wall but leaving an annular gap between the periphery of the bafile and. the vessel, and an outlet from said vessel from near the top of the lower part thereof beneath said baifle.

3. Apparatus for purifying paper pulp comprising a vessel of circular cross section, a top provided with a spiral inlet pipe on the periphery of said vessel, and an outlet pipe from said vessel opening near its axis and arranged above the inlet, a baflie substantially dividing said vessel into an upper and lower portion, there bein a narrow annular gap between the periphery of said baffle and the wall of the vessel, said baiile also having a central opening therein, a plate beneath said baffle shielding the space beneath from the flow through said opening, and an outlet pipe leading upward from said opening out of the vessel.

4. An apparatus for the continuous cleaning and separating particularly of paper making pulp, comprising an outer principal container having an upper portion of truncated conical form and a trusts-conical lower portion, an inner arated materials from the upper and lower parts container member having an inverted truncated conical lower portion with an inlet at its lower end and cylindrical upper portion with an outlet at its upper end, an inlet of spiral form on the top of the outer container adapted to introduce the paper pulp to be treated tangentially into the outer container at high speed, the cleaned pulp and lighter constituents passing concentrically upwards while the heavier constituents pass downwards, means for conveying away the sepof the apparatus, a depending circular hood bafile' located concentrically within the lower end of the truncated conical part of the outer container and adapted to form therewith a comparatively narrow and deep annular gap, said hood having a central opening, a concentric open-ended pipe of comparatively small diameter fitted in said opening and extending upwards through the top of the container, and a the central opening in the hood and adapted to baiiie said opening.

5. An apparatus for the continuous cleaning and separating particularly of paper making pulp, comprising an outer principal container having an upper portion of truncated conical form and a frusto-comcal lower portion, an inner container member having an inverted truncated conical lower portion with an inlet at its lower end and cylindrical upper portion with an outlet at its upper 'end, an inlet of spiral form on the top of the outer container adapted to introduce the paper pulp to be treated tangentially into the outer container at high speed, the cleaned pulp and lighter constituents passing concentrically disc spaced slightly belowupwards while the heavier constituents pass downwards, means for conveying away the separated materials from the upper and lower parts of the apparatus, an inverted conical bottom sectionconnected to the cylindrical part of the outer container, and a sluice valve container means comprising a lower container in communication at its top with the lower part of the principal container, and a controlling valve at the top of the lower container and a controlling valve at the bottom end thereof.

6. An apparatus for the continuous cleaning and separating particularly of paper making pulp, comprising an outer principal container having an upper portion of truncated conical form and a frusto-conical lower portion, an inner container member having an inverted truncated conical lower portion with an inlet at its lower end and cylindrical upper portion with an outlet at its upper end, an inlet of spiral form on the top of the outer container adapted to introduce the paper material to be treated tangentially into the outer container at high speed, the cleaned pulp and lighter constituents passing concentrically upwards while the heavier constituents pass downwards, means for conveying away the separated pulp from the upper and lower parts of the apparatus, an inverted conical bottom section connected to the cylindrical part the outer container, a sluice valve container connected to the lower part of the outer container, said sluice valve container comprising a lower container in communication at its top with the lower part of the principal container, a controlling valve at the top of the lower container, and a controlling valve at the bottom end of the lower container, a water supply pipe connected with the bottom end of the lower container, means for opening and closing the said pipe, an air pipe connected with the top part of the lower container, and means for opening and closing the air pipe.

7. An apparatus for the continuous cleaning and separating particularly of paper making pulp,

comprising an outer principal container having an upper portion of truncated conical form and a frusto-conical lower portion, an inner container member having an inverted truncated conical lower portion with an inlet at its lower end and cylindrical upper portion with an outlet at its upper end, an inlet of spiral form on the top of the outer container adapted to introduce the paper pulp to be treated tangentially into the outer container at high speed, the cleaned pulp and lighter constituents passing concentrically upwards while the heavier constituents pass downwards, means for conveying away the separated pulp from the upper and lower parts of the apparatus, an inverted conical bottom section connected to the cylindrical part of the outer container, a sluice valve container connected to the lower part of the bottom section, and a valve controlled supply pipe for dilution water opening into the lower part of the principal container.

8. An apparatus for the continuous cleaning and separating particularly of paper making pulp, comprising an outer principal container having an upper portion and a lower portion, an inner container member having an inlet at its lower end and an outlet at its upper end, an inlet of spiral form on the top of the outer container adapted to introduce the paper pulp to be treated tangentially into the outer container at high speed, the cleaned pulp and lighter constituents passing concentrically upwards while the heavier constituents pass downwards, means for conveying away the separated materials from the upper and lower parts of the apparatus, 8. depending circular hood baffle located concentrically within the upper portion of the outer container and adapted to form therewith a comparatively narrow and deep annular gap, said hood having a central opening, a concentric open-ended pipe of comparatively small diameter fitted in said opening and extending upwards through the top or the container, and a disc spaced slightly below the central opening in the hood and adapted to bafile said opening.

9. An apparatus for the continuous cleaning and separating particularly of paper making pulp, comprising an outer principal container having an upper portion and a lower portion, an inner container member having an inlet at its lower end and cylindrical upper portion with an outlet at its upper end, an inlet of spiral form on the top of the outer container adapted to introduce the paper material to be treated tangentially into the outer container at high speed, the cleaned pulp and lighter constituents passing concentrically upwards while the heavier constituents pass downwards, means for conveying away the separated pulp from the upper and lower parts of the apparatus, a sluice valve container connected to the lower part of the outer container, said sluice valve container comprising a lower container in communication at its top with the lower part of the principal container, a controlling valve at the top of the lower container, and a controlling valve at the bottom end of the lower container, a water supply pipe connected with the bottom end of the lower container, means for opening and closing the said pipe, an air pipe connected with the top part of the lower container, and means for opening and closing the air pipe.

10. Apparatus for purifying paper pulp comprising a vessel of circular cross-section, a spiral inlet on the periphery of said vessel near its top by which pulp supplied under pressure is caused to form a vortex in said vessel, an outlet from the top of said vessel opening near its axis for delivery of purified pulp, a baiile transverse to the axis of said vessel substantially but not wholly dividing said inlet and outlet and a settling chamber and protecting the latter from the swirl of the vortex but permitting limited passage of pulp from the one chamber to the other, and an outlet from said settling chamber leading out of the vessel to permit escape of some liquid and thereby cause a current from the vortex chamber to the settling chamber.

11. A method of purifying paper pulp comprising setting up a downwardly flowing vortex of pulp, withdrawing in an upward direction from the lower part of said vortex and from the center thereof the greater part of the pulp at least in part freed from impurities, maintaining a relatively quiescent body of pulp communicating with the lower end of the vortex into which separated impurities may settle, and constantly withdrawing from said quiescent body a small proportion of the pulp thereby producing a slight downward current from said vortex-into said quiescent body to carry separated impurities into the latter.

ANDRE omens. 

